:root{
  --harvard-crimson:#A41034;
  --harvard-crimson-dark:#7A0C26;
  --ink:#1f1f1f;
  --muted:#666;
  --paper:#f8f6f1;
  --white:#fff;
  --line:#d9d5cc;
  --soft:#f0ede6;
  --gold:#c9a227;
  --shadow:0 12px 30px rgba(31,31,31,.08);
  --radius:4px;
  --max:1180px;
  --sans:Arial, Helvetica, sans-serif;
  --serif:Georgia, "Times New Roman", serif;
}
*{box-sizing:border-box}
html,body{margin:0;min-height:100%;background:var(--paper);color:var(--ink)}
body{font-family:var(--sans);line-height:1.55}
a{color:inherit}
button,a{font:inherit}
button{cursor:pointer}

.slide-page{overflow-x:hidden;overflow-y:auto}
.slide-root{min-height:100vh;min-height:100dvh;display:grid;grid-template-rows:auto minmax(0,1fr) auto;position:relative}
.topbar,.slide-footer{
  background:rgba(255,255,255,.96);
  border-color:var(--line);
  z-index:20;
}
.topbar{
  min-height:58px;border-bottom:1px solid var(--line);
  display:flex;align-items:center;justify-content:space-between;
  padding:10px 24px;gap:12px;
}
.slide-footer{border-top:1px solid var(--line);padding:10px 20px}
.footer-inner{max-width:var(--max);margin:auto;width:100%;display:flex;align-items:center;gap:10px}
.progress-track{height:4px;background:#e7e3dc;flex:1;min-width:80px}
.progress-fill{height:100%;background:var(--harvard-crimson);width:0;transition:width .2s ease}
.counter{min-width:68px;text-align:center}

.btn{
  display:inline-flex;align-items:center;justify-content:center;
  min-height:36px;padding:7px 12px;border:1px solid #bdb8ae;
  border-radius:var(--radius);background:#fff;color:var(--ink);
  text-decoration:none;transition:.15s ease;
}
.btn:hover{border-color:var(--harvard-crimson);color:var(--harvard-crimson)}
.btn.primary{background:var(--harvard-crimson);border-color:var(--harvard-crimson);color:#fff}
.btn.primary:hover{background:var(--harvard-crimson-dark)}
.btn.disabled{opacity:.45;pointer-events:none}

.sidebar{
  position:fixed;z-index:50;inset:0 auto 0 0;width:300px;
  background:#fff;border-right:1px solid var(--line);
  transform:translateX(-100%);transition:transform .2s ease;
  box-shadow:var(--shadow);padding:20px;
}
.sidebar.open{transform:translateX(0)}
.sidebar-head{display:flex;justify-content:space-between;align-items:flex-start;gap:12px;padding-bottom:16px;border-bottom:2px solid var(--harvard-crimson)}
.eyebrow,.tag{
  font-size:.74rem;text-transform:uppercase;letter-spacing:.13em;
  color:var(--harvard-crimson);font-weight:700;
}
.sidebar strong{font-family:var(--serif);font-size:1.05rem}
.nav-list{display:grid;gap:3px;margin-top:16px;max-height:calc(100vh - 130px);overflow:auto}
.nav-list a{
  padding:9px 10px;border-left:3px solid transparent;text-decoration:none;color:#444;
}
.nav-list a:hover,.nav-list a.active{background:var(--soft);border-left-color:var(--harvard-crimson);color:var(--harvard-crimson)}
.overlay{display:none;position:fixed;inset:0;background:rgba(0,0,0,.25);z-index:40}
.overlay.open{display:block}

.slide-main{position:relative;overflow:auto;min-height:0;-webkit-overflow-scrolling:touch}
.slide{
  display:none;min-height:calc(100vh - 116px);
  padding:clamp(28px,5vw,72px) 24px;
}
.slide.active{display:block}
.slide-content{max-width:var(--max);margin:0 auto;width:100%}
.slide-content.two-col{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:clamp(24px,5vw,72px);align-items:center}
.slide-title{
  margin:0 0 24px;font-family:var(--serif);font-size:clamp(2rem,4vw,3.3rem);
  line-height:1.08;color:var(--harvard-crimson);font-weight:700;
}
.title-xl{
  margin:.35rem 0 1rem;font-family:var(--serif);
  font-size:clamp(3rem,7vw,6.4rem);line-height:.98;letter-spacing:-.035em;
  color:var(--harvard-crimson);
}
.hero-copy{font-family:var(--serif);font-size:clamp(1.15rem,2vw,1.5rem);max-width:760px;color:#4a4a4a}
.mini{color:#4a4a4a;font-size:1rem}
.slide p{max-width:850px}
.slide h3{font-family:var(--serif);margin-top:0;color:#333}
.shine{
  position:absolute;right:7%;top:8%;width:240px;height:240px;
  border-radius:50%;background:rgba(164,16,52,.07);filter:blur(1px);
  pointer-events:none;
}
.grid-auto{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px}
.glass,.card,.meeting-card{
  background:#fff;border:1px solid var(--line);border-radius:var(--radius);
  box-shadow:var(--shadow);padding:20px;
}
.card{font-size:1.02rem}
.code{
  margin:0;background:#1d1d1d;color:#f5f2eb;padding:20px;border-radius:var(--radius);
  overflow:auto;font:14px/1.65 "SFMono-Regular",Consolas,"Liberation Mono",monospace;
  border-left:4px solid var(--harvard-crimson);
}
.code code{white-space:pre}
.demo-area{
  min-height:120px;padding:22px;display:grid;place-items:center;
  background:#eee;border:1px solid var(--line);color:#222;
}
.demo-area[style]{background:#eee !important;color:#222 !important}
.mock,.sample-game-card{
  background:#fff;border:1px solid var(--line);box-shadow:var(--shadow);border-radius:var(--radius);
}
.mock{padding:14px}
.mockbar{padding:8px 10px;border-bottom:1px solid var(--line);font-size:.85rem;color:#666}
.mock .card{box-shadow:none;border:0;padding:14px}
.float{animation:none}
.flex-demo-row{display:flex;flex-wrap:wrap;gap:16px}
.sample-game-card{padding:18px;flex:1 1 180px;min-width:160px}
.choice{
  padding:16px;border:1px solid var(--line);background:#fff;text-align:left;
  border-radius:var(--radius);font-weight:700;
}
.choice:hover{border-color:var(--harvard-crimson)}
.choice.correct{background:#eef6ee;border-color:#3c7a3c}
.choice.wrong{background:#fbefef;border-color:#a33}
.flowchart-row{display:flex;flex-wrap:wrap;align-items:center;justify-content:center;gap:10px}
.flow-node{background:#fff;border:1px solid var(--harvard-crimson);padding:14px 18px;border-radius:var(--radius);font-family:var(--serif)}
.flow-arrow{color:var(--harvard-crimson);font-weight:700}
.badge{
  display:inline-block;padding:4px 8px;border-radius:999px;
  background:var(--harvard-crimson);color:#fff;font-size:.72rem;font-weight:700;
}
.badge.muted{background:#777}
.meeting-grid{
  max-width:var(--max);margin:30px auto;display:grid;
  grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:18px;padding:0 24px;
}
.meeting-card h2{font-family:var(--serif);color:var(--harvard-crimson);font-size:1.45rem}
.hero-panel{
  max-width:var(--max);margin:28px auto 0;padding:clamp(28px,5vw,60px) 24px;
  border-bottom:4px solid var(--harvard-crimson);
}
.hero-panel h1{font-family:var(--serif);font-size:clamp(2.5rem,6vw,5rem);line-height:1;color:var(--harvard-crimson);margin:.3em 0}
.page-shell{min-height:100vh}
.page-shell>.btn:first-child{display:block;width:max-content;margin:20px auto 0}
ol,ul{padding-left:1.3rem}
blockquote{border-left:4px solid var(--harvard-crimson);margin:20px 0;padding:10px 18px;background:#fff}
hr{border:0;border-top:1px solid var(--line);margin:28px 0}

@media (max-width:800px){
  .slide{min-height:calc(100vh - 128px);padding:28px 18px}
  .slide-content.two-col{grid-template-columns:1fr}
  .footer-inner{flex-wrap:wrap;align-items:stretch}
  .footer-inner .btn,.footer-inner .counter{flex:1 1 calc(50% - 5px)}
  .progress-track{order:10;flex-basis:100%}
  .counter{min-width:0}
  .topbar{padding:9px 12px}
  .topbar .btn{font-size:.85rem}
  .title-xl{font-size:clamp(2.6rem,13vw,4.5rem)}
}
@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{animation:none!important;transition:none!important}
}